Semiconductor manufacturing system

ABSTRACT

Disclosed is a technique for effectively suppressing the generation of particles resulting from peeling-off of unnecessary films that have unavoidably adhered to the inner surface of the reaction tube of an ALD film-forming apparatus. A precoating process utilizing ALD is performed to deposit a metal oxide film, e.g., an aluminum oxide film, onto the unnecessary films, in order to prevent peeling-off of the unnecessary films. The type and/or position of the nozzle for supplying ozone, as a precoat gas, into the reaction tube during the precoating process is different from that of the nozzle for supplying ozone, as a film-forming gas, into the reaction tube during forming of a film on a semiconductor substrate.

TECHNICAL FIELD

The present invention relates to semiconductor manufacturing system andparticularly to coating apparatus for forming a film of a desiredthickness by repeating atomic or molecular level deposition. Moreparticularly, the Invention relates to a technique of effectivelyprecoating the inside of the reaction vessel to prevent the generationof particles.

BACKGROUND ART

With higher integration of semiconductor devices, the miniaturization oftheir device pattern progresses. For example, 1-gigabit dynamic randomaccess memory (DRAM) has been used in practical applications. Such largecapacity DRAM employs elements reduced in dimension and hence in surfacearea. Since DRAM uses the amount of charge stored on its memory cellcapacitors as stored information, these capacitors must have acapacitance greater than a certain value. Therefore, memory cellcapacitors currently have a very high aspect ratio. Conventionally, CVD(Chemical Vapor Deposition) is used to form capacitive dielectric filmsfor capacitors. However, it is difficult by CVD to uniformly form adielectric film in a high aspect ratio groove with a high coverage. Inorder to retain its stored data, a memory cell capacitor must have highcapacitance and a low leakage current, which requires the formation ofthe thinnest possible uniform film.

In recent years, in order to solve this problem, ALD (Atomic LayerDeposition) has been used, which repeatedly deposits a thickness of afilm material on the order of an atomic layer to form a film having adesired thickness.

A process, which repeatedly depositing a thickness of a film material onthe order of a molecular layer to form a film having a desiredthickness, is referred to as MLD (molecular layer deposition) to bedistinguished from ALD in some cases. However, in this specification,the both techniques are commonly referred to as ALD, since they arebased on the same principle. In a case where a hafnium oxide(hereinafter referred to as an “HfO”) film is formed on a semiconductorsubstrate by ALD, a gas supply cycle consisting of the supply oftetrakis(ethylmethylamino)hafnium (hereinafter abbreviated as “TEMAH”),which is an organic metal material, and the supply of ozone (O₃) isrepeated a plurality of times while maintaining the semiconductorsubstrate at a predetermined temperature. The reaction vessel isevacuated and purged by inert gas after the supply of one gas and beforesupply of the other to ensure that the gases react only on thesemiconductor substrate. An HfO film having a thickness on the order ofan atomic layer is formed on the semiconductor substrate during eachcycle. The above gas supply cycle is repeated a predetermined number oftimes determined depending on desired thickness, so that an HfO film canbe formed with excellent film-thickness reproducibility.

ALD is advantageous in its excellent film-thickness reproducibility, butis disadvantageous in its long film-forming time. For example, informing an HfO film, one cycle deposits a film of approximately 0.1 nm.Thus, 50 cycles are required to form a film of thickness of 5 nm. Ifeach cycle takes 1 minute, the total film forming time will beapproximately 50 minutes. Therefore, the use of a batch-type system ispreferable to a single substrate processing system in terms ofproductivity.

FIG. 5 shows the configuration of a conventional batch-type ALD systemfor forming an HfO film; and FIG. 6 shows a piping system associatedwith this system. Referring to FIG. 5, a vacuum exhaust port 1103 isprovided at the top of a reaction tube 1102 defining a reaction chamber1101. The vacuum exhaust port 1103 is connected to a vacuum pump 1105through an evacuation pipe provided with a pressure adjusting valve1104. A boat 1108 having a plurality of semiconductor substrates 1107mounted therein is supported on a boat loader 1106 and loaded in thereaction chamber 1101. A heater 1109 is provided around the reactiontube 1102 to heat the semiconductor substrates.

Liquid TEMAH is supplied from a TEMAH supply source 1110 through aliquid flow rate adjuster 1111 to a vaporizer 1112, in which the liquidTEMAH is vaporized and a TEMAH gas, as a source gas, is then deliveredinto the reaction chamber 1101 through a TEMAH nozzle 1113. Nitrogen gas(N₂) is supplied from a nitrogen supply source 1114 to the vaporizer1112 through a flow rate adjuster 1115 to aid vaporization of the liquidTEMAH. Oxygen gas (O₂) is supplied from an oxygen supply source (notshown) through a flow rate adjuster (not shown) to an ozone generator(not shown) in which the oxygen gas is converted into ozone which is anoxidizer. The ozone is then delivered into the reaction chamber 1101through an ozone nozzle 1113. Further, nitrogen gas used as a purge gasis supplied from the nitrogen gas supply source 1114 to the reactionchamber 1101 through a flow rate adjuster 1116 and a nitrogen gas nozzle1113. There are plural nozzles 1113 each dedicated to a different gas,although only one nozzle 1113 is shown in FIG. 5 for simplicity.

When HfO films are formed on the semiconductor substrates using thesystem having the configuration shown in FIG. 5, there may be adifference in thickness or quality of the films between thesemiconductor substrates mounted in the lower portion and the upperportion of the boat 1108. The reason is that the semiconductorsubstrates disposed in the upper portion of the reaction chamber 1101cannot receive sufficient amounts of TEMAH gas and ozone, since theTEMAH gas and the ozone delivered from L-shaped nozzles 1113, which areprovided in the lowest portion of the reaction chamber 1101, are mostlyconsumed by the reaction occurring in the lower portion of the reactionchamber 1101. Unlike CVD, in ALD, the supply of excessive amount ofsource gas does not result in formation of an unnecessarily large filmthickness. Therefore, excessive TEMAH gas may be supplied into thereaction chamber 1101 to cause a sufficient amount of TEMAH gas to reachthe upper portion of the reaction chamber 1101. On the other hand, ozonehas a short life under elevated temperature conditions. Therefore, thesupplied ozone progressively disappears as it flows from the lowerportion to the upper portion of the reaction chamber 1101 and, as aresult, the upper portion of the reaction chamber 1101 is more likely tolack ozone. To solve this problem, it may be conceived that an excessiveamount of ozone may be supplied to the reaction chamber 1101. However,the supply of an excessive amount of ozone causes oxidation damage tothe components in the lower portion of the reaction chamber 1101, whichis not desirable. Furthermore, ozone is consumed by this oxidationreaction.

In order to solve these problems, a distributing nozzle(s) 1117 such asshown in FIG. 7 may be used. The distributing nozzle 1117 extends fromthe bottom to the top of the reaction chamber 1101 and includes nozzleholes 1118 each corresponding to respective semiconductor substratesmounted in the boat 1118. This arrangement allows processing gas,especially ozone, to be uniformly supplied to the semiconductorsubstrates. It should be noted that the TEMAH gas may be suppliedthrough an L-shaped nozzle shown in FIG. 5 or the distributing nozzleshown in FIG. 7.

Incidentally, particle reduction is a critical issue in semiconductormanufacturing. When a film is formed on the semiconductor substrates byCVD, ALD, or other chemical deposition process, deposition ofunnecessary films unavoidably occurs on the inner wall of the reactiontube and on the various components that are exposed to the atmospherewithin the reaction vessel. Peeling-off of the unnecessary films is amajor cause of the generation of particles, as is well known to those ofordinary skill in the art. Peeling-off of the unnecessary films tends tooccur when the unnecessary films have a large thickness or when theinside of the reaction vessel is exposed to the ambient atmosphere. Forexample, generation of a large quantity of particles was found after theinside of reaction vessel was exposed to the ambient atmosphere formaintenance or repair after performing deposition of HfO films for manytimes. Analysis of these particles by EDX (energy dispersive X-rayspectroscopy) revealed that they were formed of hafnium oxide. It isthought that the above generation of particles resulted from the factthat HfO films formed on the inner wall of the reaction tube absorbedmoisture and thereby peeled off when the inside of the reaction tube wasexposed to the ambient atmosphere for maintenance. It was not possibleto visually recognize the HfO particles since their sizes were verysmall (mostly 10 microns or less).

One of the possible countermeasures against the generated particles iscycle purging. A trial was conducted to reducing particles by using thecycle purging. The purging was performed by repeating a cycle consistingof an ozone flowing step, an evacuating step, and a nitrogen gas flowingstep 50 times (spending approximately 3 hours), as shown in FIG. 9. InFIG. 9, the horizontal axis is graduated in 15 sec increments. The ozoneconcentration in the ozone flowing step was 200 g/Nm³; the oxygen flowrate before the oxygen-to-ozone conversion (corresponding to the ozoneflow rate) was 10 SLM; the pressure in the reaction vessel in theevacuating step was approximately 5 Pa; and the nitrogen gas flow ratein the nitrogen gas flowing step was 10 SLM. Dummy semiconductorsubstrates were placed in the boat and heated to 300° C. The number anddistribution of particles on the dummy semiconductor substrates wereobserved after completion of every predetermined number of cycles.Various particle distribution patterns were found: locally concentratedpatterns sparsely distributed patterns, etc. FIGS. 10A and 10B show twoexamples of the observed particle distribution patterns. FIG. 11 showschange in the number of particles. The number of particles was notstably reduced even after more than 200 purge cycles (spendingapproximately 12 hours). Under such conditions, a deposition process cannot be performed.

Another possible countermeasure against the generated particles iscleaning. However, there is no established method for removing an HfOfilm by in-situ dry cleaning. Wet cleaning, on the other hand, requiresdisassembly of the system, resulting in significant downtime.Furthermore, wet cleaning should not be frequently performed, since itshortens the life of the quartz components. Replacement of componentsresults in shorter downtime. However, it is not practical since quartzcomponents are expensive.

SUMMARY OF THE INVENTION

The present invention has been devised in view of the foregoingcircumstances, and it is therefore the object of the present inventionto provide an effective, in-situ method of taking countermeasure againstparticles.

The present inventors have found that, also in a coating apparatus thatforms a film on semiconductor substrates by repeated atomic or molecularlevel depositions, a precoating process that coats unnecessary film(s)with another film is useful for reducing particles. It has also beenfound that such a precoating process can be performed very effectively,if the gas supply mode during precoating is different from the gassupply mode during film formation, in particular, if a gas nozzle for aprecoating gas is provided separately from a gas nozzle for filmformation. The present invention has been made based on those findings.

Specifically, the present invention provides a semiconductormanufacturing system including a reaction vessel and at least onefilm-forming nozzle for supplying at least one film-forming gas into thereaction vessel, configured to form a film on a semiconductor substratedisposed within the reaction vessel by supplying the film-forming gasinto the reaction vessel to repeat atomic or molecular level deposition,wherein the semiconductor manufacturing system further includes at leastone coating nozzle for supplying at least one kind of coating gas intothe reaction vessel to coat a component exposed to an atmosphere withinthe reaction vessel, wherein at least one of said at least one coatingnozzle is separated from said at least one film-forming nozzle.

In one preferred embodiment, the at least one kind of film-forming gasincludes a first film-forming gas and a second film-forming gas, and theat least one coating gas includes a first coating gas and a secondcoating gas; the first film-forming gas is the same as the first coatinggas; and a coating nozzle for supplying the first coating gas isseparated from a film-forming nozzle for supplying the firstfilm-forming gas.

In one preferred embodiment, the second film-forming gas is ametal-containing gas; the second coating gas is a metal-containing gas,and both the first film-forming gas and the first coating gas are ozone.The at least one kind of film-forming gas may include a thirdfilm-forming gas, and the third film-forming gas may be the same as thesecond coating gas.

In one preferred embodiment, the semiconductor manufacturing system is abatch-type system adapted to contain a plurality of semiconductorsubstrates in the reaction vessel to perform a film forming process tothe semiconductor substrates collectively, the reaction vessel has anexhaust port for evacuating an interior of the reaction vessel, thefilm-forming nozzle for supplying the first film-forming gas is adistributing nozzle having a plurality of nozzle holes for dischargingthe first film-forming gas toward the plurality of semiconductorsubstrates from their sides, and the coating nozzle for supplying thefirst coating gas has a nozzle hole which opens in the reaction vesselat a position farther from the exhaust port than a region in which theplurality of semiconductor devices are disposed. The semiconductormanufacturing system may be a vertical, batch-type system thataccommodates a plurality of semiconductor substrates arrayed verticallyin horizontal posture in the reaction vessel, and performs afilm-forming process to the semiconductor substrates collectively.

In the most typical embodiment of the present invention described laterwith reference to the accompanying drawings, the first film-forming gasis ozone; the second film-forming gas is TEMAH gas; the thirdfilm-forming gas is trimethyl aluminum (hereinafter abbreviated as“TMA”) gas; the first precoating gas is ozone; and the second precoatinggas is TMA gas. Further, the semiconductor manufacturing system is avertical, batch-type system that accommodates a plurality ofsemiconductor substrates arrayed vertically in horizontal posture in thereaction vessel, and performs a film-forming process to thesemiconductor substrates collectively. Further, the film-forming nozzlefor supplying the first film-forming gas (i.e., ozone) is a distributingnozzle having a plurality of nozzle holes for discharging the firstfilm-forming gas toward the plurality of semiconductor substrates fromtheir sides; and the coating nozzle for supplying the first coating gas(i.e., ozone) is an L-shaped nozzle having a nozzle hole which opens inthe reaction vessel at a position farther from an exhaust port than aregion in which the plurality of semiconductor devices are disposed.Ozone is a short-lived gas. Such a gas is supplied through thedistributing nozzle during film formation, but is supplied from aposition far away from the exhaust port during precoating so that thegas uniformly spreads within the vessel. Thereby, a film of high qualitycan be obtained during film formation, while the entire inside of thereaction vessel can be coated with a precoat film of high quality with asmall number of deposition cycles during precoating. In this way, it ispossible to effectively prevent generation of particles, and the systemcan restart in a short time period after maintenance of the system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the number of generated particles afterperforming precoating according to the present invention.

FIG. 2 is a graph showing the thickness distribution of precoat films.

FIG. 3 is a vertical cross-sectional view schematically showing theconfiguration of an ALD apparatus according to the present invention.

FIG. 4 is a schematic diagram showing a gas introducing portion of theALD apparatus according to the present invention.

FIG. 5 is a schematic vertical cross-sectional view showing an exampleof a conventional ALD apparatus.

FIG. 6 is a diagram showing a piping system in the ALD apparatus shownin FIG. 5.

FIG. 7 is a schematic vertical cross-sectional view of another exampleof the conventional ALD apparatus.

FIG. 8 is a side view schematically showing the configuration of adistributing nozzle.

FIG. 9 is a time chart illustrating a cycle purge process.

FIG. 10 is a diagram showing the distribution of particles onsemiconductor substrates in one example.

FIG. 11 is a graph showing a relationship between the number of purgecycles and the number of particles.

FIG. 12 is a time chart illustrating a precoat process.

FIG. 13 is a graph showing a relationship between the number of precoatcycles and the number of particles.

FIG. 14 is an enlarged view of a portion of the graph of FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be described in detail with reference to theresults of studies and experiments conducted by the present inventors toachieve the invention.

A precoating technique has been used to prevent the generation ofparticles resulting from peeling-off of unnecessary films in CVDapparatus. The precoating technique coats potentially peelableunnecessary films with a film (e.g., an SiO₂ film) to preventpeeling-off of the unnecessary films. The present inventors have triedto extend this technique.

The present inventors conducted an experiment in which an HfO film wascoated with an aluminum oxide (hereinafter referred to as an “AlO”)film. The AlO film was formed by an ALD process that repeats, aplurality of times, a deposition cycle consisting of a TMA gas flowingstep, an evacuating step, a nitrogen gas flowing (purging) step, anozone flowing step, an evacuating step, and a nitrogen gas flowing(purging) step which were performed in that order, as shown in FIG. 12.In FIG. 12, the horizontal axis is graduated in 5 sec increments. Thisdeposition cycle was performed under the following process conditions.The TMA gas flow rate in the TMA gas flowing step was 100 SCCM; theozone concentration in the ozone flowing step was 200 g/Nm³; the oxygenflow rate before the oxygen-to-ozone conversion (corresponding to theozone flow rate) was 10 SLM; the pressure in the reaction vessel aftereach evacuating step was approximately 5 Pa; and the nitrogen gas flowrate in the nitrogen gas flowing step was 10 SLM. Several dummysemiconductor substrates were placed in the boat and heated to 300° C.Under the aforementioned conditions, 0.1 nm of AlO film was deposited ineach cycle. Thus, a 10 nm thick AlO film was formed by 100 cycles. 100cycles spent approximately 2.5 hours.

This experiment was performed, using an ALD apparatus of the type shownin FIG. 7 (employing distributing nozzles), according to the followingsteps:

(1) performing a conventional, batch, HfO film coating process and thenexposing the reaction tube to the ambient atmosphere;

(2) performing 100 cycles of ALD precoating process under the foregoingconditions;

(3) performing a conventional, batch HfO film coating process in theprecoated reaction tube and then counting the number of particles on thesemiconductor substrates; and

(4) repeating step (2) and step (3).

FIGS. 13 and 14 are graphs illustrating the results of the experiment.FIG. 14 is an enlarged view of a portion of the graph of FIG. 13 (bothgraphs are based on the same data.) As is apparent from FIGS. 13 and 14,the number of the particles was stably reduced after 400 precoatingcycles (the resultant AlO precoat film thickness was 40 nm).

The experiment indicates that AlO film precoating is useful forpreventing peeling-off of the HfO film. However, it takes approximately10 hours to complete 400 precoating cycles. This precoating processtakes much longer time to complete than conventional SiO₂ filmprecoating processes by CVD and therefore is not practical for mostapplications.

The present inventors also attempted to combine the above cycle purgingprocess and the AlO film precoating process, but with no practicallyuseful results. Approximately 400 cycles of AlO film precoating wereneeded to reduce the number of particles regardless of the number ofpurge cycles.

The inventors endeavored to develop a technique of effectively formingan aluminum oxide precoating to sufficiently prevent peeling-off of thefilm. In the course of the development of such a technique, theinventors have come to a hypothesis that the use of the distributingnozzle, which is used to effectively supply ozone during desired filmformation, rather avoids formation of a high-quality precoating.

To verify this hypothesis, an experiment was performed by using the ALDapparatus shown in FIG. 3, Note that the ALD apparatus shown in FIG. 3is a film-forming system (semiconductor manufacturing system) in oneembodiment of the present invention, as can be seen from the followingdescription. The ALD apparatus shown in FIG. 3 will now be described.

The ALD apparatus shown in FIG. 3 differs from those described in the“Background Art” section with reference to FIGS. 5 and 7 in that it hasa different gas supply system. Duplicative description of the samecomponents is thus omitted.

The ALD apparatus shown in FIG. 3 includes a distributing nozzle 107 andL-shaped nozzles 108. The distributing nozzle 107 extends verticallywithin the reaction chamber 1101 in the longitudinal direction of theboat 1108, that is, in the direction of arrangement of the semiconductorsubstrates. The distributing nozzle 107 is configured to jet a gas,through nozzle holes thereof each arranged at positions corresponding torespective semiconductor substrates, toward respective semiconductorsubstrates from their sides. Each L-shaped nozzle 108 is provided at thelowest peripheral portion of the reaction chamber 1101 and configured tosupply a gas through a single nozzle hole thereof from the bottom towardthe top of the boat 1108. Note that, in the ALD apparatus shown in FIG.3, all components exposed to the atmosphere within the reaction chamber1101 are either formed of quartz or covered with quartz.

The gas supply system for the ALD system shown in FIG. 3 is adapted toform an HfO film and an AlO film on the semiconductor substrates, aswell as to form an AlO film as a precoat film on the inner wall of thereaction tube and on the inner components of the reaction vessel thatare exposed to the atmosphere within the reaction vessel.

FIG. 4 is a schematic horizontal cross-sectional view of the manifold,or gas introducing portion, mounted in the lowermost portion of thereaction tube (or reaction vessel) 1102 of the ALD apparatus shown inFIG. 3. Gas lines for introducing various gases into the reactionchamber 1101 penetrate through the manifold. The distributing nozzle 107(see FIG. 8) or the L-shaped nozzle 108 (not shown in FIG. 4) is coupledto the tip of each gas line to discharge a gas into the reaction chamber1101. The gas supply system for the ALD apparatus shown in FIG. 3includes: an L-shaped nozzle connected to a TEMAH gas line to supplyTEMAH gas when forming HfO films on the semiconductor substrates; anL-shaped nozzle connected to a TMA gas line to supply TMA gas whenforming AlO films on the semiconductor substrates; the distributingnozzle connected to an ozone line to supply ozone when forming the bothHfO films and AlO films on the semiconductor substrates; an L-shapednozzle connected to a TMA gas line to supply TMA gas when formingprecoat films on the inner components of the reaction vessel; and anL-shaped nozzle connected to an ozone line to supply ozone when formingprecoat film on the inner components of the reaction vessel. Only someof these nozzles are shown in FIG. 3 for simplicity.

Note that, when an HfO film is formed as a capacitive dielectric film,it is common to form an AlO film on the HfO film to provide enhancedinsulation. Therefore, the ALD apparatus shown in FIGS. 3 and 4 includesa nozzle for forming an AlO film on the semiconductor substrates, asdescribed above.

Note that, the ALD apparatus may further include a nitrogen gas supplynozzle for purging (preferably having an L-shape) (see FIG. 4). However,the nitrogen gas used as a purge gas is more preferably supplied throughnozzles for supplying TEMAH gas and TMA gas. There may be a plurality ofnozzles each having the same task. Further, a plurality of nozzles maybe disposed locally and collectively, as shown in FIG. 4, or they may bedistributed along the circumference of the reaction tube 1102.

The nozzle holes of the L-shaped nozzles 108, especially those forsupplying precoating gases, are arranged at positions ensuring that thegases discharged from the nozzles is sufficiently supplied to thesurfaces of the components in the lower portion of the reaction chamber1101, such as a plate-like member which is a part of the boat loader1106 (i.e., the cover for closing the lower end opening (furnace throat)of the reaction tube 1102) and a insulating tube. Preferably, the nozzleholes of the L-shaped nozzles 108 for supplying precoating gases arearranged in the reaction chamber 1101 at positions farthest from thevacuum exhaust port 1103. In the example shown in FIG. 3, the nozzleholes of the L-shaped nozzles 108 are located approximately 100 mm abovethe bottom surface of the reaction chamber 1101, i.e., the top surfaceof the cover described above.

Next, an experiment conducted by using the ALD apparatus shown in FIG. 3will be described.

(1) A conventional, batch HfO film coating process (by ALD) wasperformed a predetermined number of times by using the ALD apparatusshown in FIG. 3. The inside of the reaction vessel was then exposed tothe ambient atmosphere. At that time, the TEMAH gas was supplied throughthe L-shaped nozzle 168 and the ozone was supplied through thedistributing nozzle 107.

(2) 100-cycle AlO precoating process was performed by ALD. The AlOprecoating process was performed by repeating, a plurality of times, anALD deposition cycle consisting of a TMA gas flowing step, an evacuatingstep, a nitrogen gas flowing (purging) step, an ozone flowing step, anevacuating step, and a nitrogen gas flowing (purging) which areperformed in that order, as shown in FIG. 12. In FIG. 12, the horizontalaxis is graduated in 5 sec increments. The TMA gas flow rate in the TMAgas flowing step was 100 SCCM; the ozone concentration in the ozoneflowing step was 200 g/Nm³; the oxygen flow rate before theoxygen-to-ozone conversion (corresponding to the ozone flow rate) was 10SLM; the pressure in the reaction vessel in the evacuating steps wasapproximately 5 Pa; and the nitrogen gas flow rate in the nitrogen gasflowing step was 10 SLM. Several dummy semiconductor substrates wereplaced in the boat and heated to 300° C. Both the TMA gas and ozone weresupplied through the L-shaped nozzles.

(3) A conventional, batch HfO film forming process (by ALD) wasperformed once, and then the semiconductor substrates were checked forparticles. The HfO film forming conditions may be understood just bysubstituting “TEMAH” for “TMA” in FIG. 12. The TEMAH gas flow rate inthe TEMAH gas flowing step was 1 ml/min (liquid basis). The flow ratesof the other gases and the temperature and pressure conditions were thesame as those for forming the AlO film described above. At that time,the TEMAH gas was supplied through an L-shaped nozzle 108 and the ozonewas supplied through the distributing nozzle 107.

As shown in the graph of FIG. 1, as a result of the 100-cycleprecoating, the number of particles (larger than 0.12 microns in size)generated after the subsequent HfO film formation was 20, sufficientlysmall. It took approximately 2.5 hours to complete the 100-cycleprecoating. It was thus found that the time required for precoating wasreduced to quarter as compared with the case where a distributing nozzlewas used as an ozone supply nozzle in which the time required forprecoating was approximately 10 hours, as previously described withreference to the previous experiment result.

Silicon pieces were placed at positions 101 to 106 within the reactionchamber 1101 before the above step (2) (see FIG. 3). The position 101 islocated on the inner surface of the cover of the boat loader 1006 (lowerthan the nozzle holes of the L-shaped gas supply nozzles 108); thepositions 102 and 103 are on heat shielding plates of the heatInsulating tube of the boat loader 1006; the position 104 is on thebottom of the boat 1108; the position 105 is on the dummy semiconductorsubstrate placed in the lower portion of the boat 1108; and the position106 is on the dummy semiconductor substrate placed in the centralportion of the boat 1108. The thickness of the AlO precoat film formedon each silicon pieces was measured after the above step (2). Inaddition, a comparative experiment was performed in which: adistributing nozzle for forming the HfO film was used instead of anL-shaped gas supply nozzle to supply ozone when forming the AlO precoatfilm (the other conditions are the same as in the above experiment); andthe thickness of the AlO precoat film formed on the silicon pieces ateach of the positions 101 to 106 was also measured.

FIG. 2 is a graph illustrating the results of these experiments. In FIG.2, symbol A denotes the thickness of the precoat film formed when theozone was supplied through an L-shaped gas supply nozzle; and symbol Bdenotes the thickness of the precoat film formed when the ozone wassupplied through the distributing gas supply nozzle. At the positions104, 105 and 106 in the boat 1108, there was no difference in thethickness of the AlO precoat films depending on the type of the nozzle.On the other hand, at the positions 101, 102 and 103, which are lowerthan the boat, the AlO precoat film formed by using the L-shaped gassupply nozzle was approximately 15% thicker than that formed by usingthe distributing gas supply nozzle.

The results of the experiments are summarized below.

(a) In the case where the ozone was supplied through the distributinggas supply nozzle, the number of particles was reduced to anon-problematic level when the thickness of the AlO precoat film reachedapproximately 40 nm (400-cycle precoating).

(b) In the case where the ozone was supplied through the L-shaped gassupply nozzle, the number of particles was reduced to a non-problematiclevel when the thickness of the AlO precoat film reached approximately11 nm (100-cycle precoating).

(c) At positions lower than the boat, the AlO precoat film formed byusing the L-shaped gas supply nozzle was thicker than that formed byusing the distributing gas supply nozzle, but only by 15%, after100-cycle AlO precoating.

The present inventors think the reasons for the above results (a), (b),and (c) are the following.

It is apparent that peeling off of the HfO film and hence the generationof particles can be more effectively prevented in the case where an AlOprecoat film is formed by supplying ozone using an L-shaped gas supplynozzle, as compared with the case where a distributing gas supply nozzleis used. The reason for this relates to the quality or coveringproperties of the precoat film rather than its thickness. If ozone issupplied through the distributing gas supply nozzle. It takes a longtime for the ozone to reach the lower region of the reaction vesselopposite to the vacuum exhaust port. Thus, a significant amount of ozonemay disappear before reaching that region. As a result, the AlO precoatfilm of good quality can not be formed in the lower region of thereaction vessel. Thus, a large thickness is required in order to achievethe desired precoating effect with an AlO precoat film of poor quality.On the other hand, when the ozone is supplied through an L-shaped gassupply nozzle, it uniformly fills the reaction vessel and flows smoothlyfrom the nozzle toward the vacuum exhaust port. This allows the precoatfilm to be of good quality and hence have the desired precoating effecteven if it has a relatively small thickness. Note that the boat holds nowafer or only several dummy wafers during the precoating process.Therefore, it is not disadvantageous that the L-shaped gas supply nozzleis located far away from the exhaust port.

Although the present invention has been described, taking formation ofan HfO film and an AlO precoat film as an example, based on an ALDsystem having a specific structure, the prevent invention is not limitedto the foregoing embodiments. It will be appreciated by those skilled inthe art that the broadest scope of the present invention is that, if theposition of a nozzle for forming a film on the semiconductor substrates(i.e., a film-forming gas nozzles) are not suitable for forming aprecoat film, a nozzle for supplying a process gas to form a precoatfilm (a precoating gas nozzle) may be provided separately from thefilm-forming gas nozzle, allowing the process gas for precoating to besupplied to an appropriate location within the reaction vessel.Therefore, in a case where another type of film is formed, the presentinvention is applicable. Further, the present invention has beendescribed while focusing on the nozzle for supplying ozone gas whenforming a film on the semiconductor substrates and to the nozzle forsupplying ozone gas for precoating. Since ozone has a short life, it istrue that the advantageous effect of the present invention is bestachieved by providing different nozzles for supplying ozone when forminga film on the semiconductor substrates and for supplying ozone whenforming a precoat film to allow ozone to be supplied from optimumpositions. However, for example, it is possible that, for example, whenforming an AlO film on the semiconductor substrates, the TMA gas may besupplied through a distributing nozzle. In this case, it is consideredthat an AlO precoat film of better quality (although the difference maynot be so large as compared with a case of ozone) can be formed by usingan L-shaped gas supply nozzle as a nozzle for supplying the TMA gasduring precoating. In addition, it will be appreciated by those skilledin the art that the advantageous effects of the present invention may beexpected not only in a case where the film to be formed on thesemiconductor substrates is an HfO film and the precoat film is an AlOfilm, but also in a case those films are of different types (althoughthe advantageous effect may not be the same degree). Further, althoughthe present invention achieves most remarkable advantageous effects ifit is applied to a vertical batch system, the advantageous effects canbe achieved even if the present invention is applied to another type ofbatch system or a single substrate processing system.

1. A semiconductor manufacturing system, including a reaction vessel andat least one film-forming nozzle for supplying at least one film-forminggas into the reaction vessel, configured to form a film on asemiconductor substrate disposed within the reaction vessel by supplyingthe film-forming gas into the reaction vessel to repeat atomic ormolecular level deposition, wherein the semiconductor manufacturingsystem further includes at least one coating nozzle for supplying atleast one kind of coating gas into the reaction vessel to coat acomponent exposed to an atmosphere within the reaction vessel, and atleast one of said at least one coating nozzle is separated from said atleast one film-forming nozzle.
 2. The semiconductor manufacturing systemaccording, to claim 1, wherein: said at least one kind of film-forminggas includes a first film-forming gas and a second film-forming gas, andsaid at least one coating gas includes a first coating gas and a secondcoating gas; the first film-forming gas is the same as the first coatinggas; and a coating nozzle for supplying the first coating gas isseparated from a film-forming nozzle for supplying the firstfilm-forming gas.
 3. The semiconductor manufacturing system according toclaim 2, wherein: the second film-forming gas is a metal-containing gas;the second coating gas is a metal-containing gas; and both the firstfilm-forming gas and the first coating gas are ozone.
 4. Thesemiconductor manufacturing system according to claim 2, wherein: thesemiconductor manufacturing system is a batch-type system adapted toaccommodate a plurality of semiconductor substrates in the reactionvessel to perform a film forming process to the semiconductor substratescollectively; the reaction vessel has an exhaust port for evacuating aninterior of the reaction vessel; the film-forming nozzle for supplyingthe first film-forming gas is a distributing nozzle having a pluralityof nozzle holes for discharging the first film-forming gas toward theplurality of semiconductor substrates from their sides; and the coatingnozzle for supplying the first coating gas has a nozzle hole which opensin the reaction vessel at a position farther from the exhaust port thana region in which the plurality of semiconductor substrates aredisposed.
 5. The semiconductor manufacturing system according to claim4, wherein: the second film-forming gas is a metal-containing gas; thesecond coating gas is a metal-containing gas; and both the firstfilm-forming gas and the first coating gas are ozone.
 6. Thesemiconductor manufacturing system according to claim 2, wherein: saidat least one kind of film-forming gas includes a third film-forming gas;and the third film-forming gas is the same as the second coating gas.